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1 [1] (May 14, 2026)

handle is hein.crs/govetzf0001 and id is 1 raw text is: Congressional Research Service Informing the legisiitive debate since 1914 Updated May 14, 2026 Defense Primer: Hypersonic Boost-Glide Weapons The U.S. Department of Defense (DOD; currently using a secondary Department of War designation under Executive Order 14347 dated September 5, 2025) is pursuing two types of hypersonic weapons technologies: boost-glide systems that place a maneuverable glide vehicle atop a ballistic missile or rocket booster, and cruise missiles that would use high-speed, air-breathing engines known as scramjets to travel to hypersonic speeds. This In Focus addresses only the first of these technologies. DOD's FY2026 budget request for hypersonic weapons was $3.9 billion, down from $6.9 billion in FY2025; the department did not provide a topline for its FY2027 request. Pentagon officials have stated that hypersonic weapons could attack priority targets promptly and with improved accuracy without facing defeat by an adversary's air or missile defense systems. Pentagon officials have also expressed concerns about advances in hypersonic weapons technologies in Russia and China, as well as about the potential threats to U.S. and allied forces and territory. Congress may consider the implications of these systems for authorizations, appropriations, and oversight. Characteristics of Hypersonkc Glide eh es Hypersonic glide vehicles (HGVs), like all weapons delivered by medium- and longer-range rocket boosters, can travel at speeds of at least Mach 5, or about 1 mile per second. The key difference between missiles armed with HGVs and missiles armed with ballistic reentry vehicles (i.e., those that travel on a ballistic trajectory throughout their flight) is not their speed, but their ability to maneuver and change course after they are released from their rocket boosters. In addition, although it is not necessary, many concepts for the delivery of HGVs presume that the boosters will launch along a flatter, or depressed, trajectory than standard ballistic missiles, and will release their gliders at a lower altitude of flight (see Figure 1). Figure I. Flight Trajectory of Ballistic Missiles vs. Hypersonic Boost-Glide Weapons Source: CRS image based on an image in Gliding missiles that fly faster than Mach 5 are coming, The Economist, April 6, 2019. Taken together, the HGV's novel trajectory and maneuverability in flight would complicate a U.S. effort to detect, track, and defend against an attack. The United States would likely detect the booster's launch, as it would for the launch of any ballistic missile, but it would not be able to predict the HGV's flight path. In addition, although an HGV launched by a rocket booster would reach its target far more quickly than a warhead delivered by an aircraft or subsonic cruise missile (in minutes instead of hours), it would not travel faster than a ballistic reentry vehicle. However, it would be more difficult to predict the intended target and to direct missile defense interceptors toward the attacking HGV. Hypersonic Bost-Gide Programs United States When the United States began to assess the military utility of hypersonic boost-glide weapons in the early 2000s, it sought to develop longer-range systems that could reach deep into an adversary's territory to attack defended, hardened, and time-urgent targets. More recently, the Pentagon has increased funding and accelerated development programs for shorter and intermediate-range boost-glide systems that could conduct prompt attacks against heavily defended targets in regional conflicts. The Navy, Army, and Air Force each maintain hypersonic boost-glide programs. (Details on these programs can be found in CRS Report R4581 1, Hypersonic Weapons: Background and Issuesfor Congress, by Kelley M. Sayler.) Unlike Russia and China, the United States is not known to be developing HGVs for use with nuclear warheads. As a result, U.S. gliders may require greater accuracy and will be more technically challenging to develop than nuclear-armed Chinese and Russian systems. Russia Russia's HGV, known as Avangard, is equipped with a nuclear warhead and deployed on SS-19 long-range land- based ballistic missiles. While SS-19 missiles can carry six nuclear warheads on a ballistic trajectory, reports indicate that they will deploy with only one Avangard HGV. Avangard reportedly features onboard countermeasures and will be able to maneuver in flight so that it can evade U.S. ballistic missile defenses. Russia conducted successful tests of Avangard in 2016 and 2018. On December 27, 2019, the Russian military announced that it had activated two SS-19 missiles equipped with Avangard. Russia views the Avangard system as a part of its nuclear retaliatory capability, ensuring that Russian missiles could penetrate U.S. ballistic missile defenses. According to the Pentagon's 2022 Missile Defense Review, the United States relies on nuclear deterrence, not ballistic missile defenses, to counter Russia's long-range missile forces. Nevertheless,